The long range goal of this research program is to probide information which will serve as a biochemical basis for an understanding of the mental retardation associated with galactosemia and phenylketonuria. This laboratory will continue to investigate those parameters of the above metabolic disorders with the aid of various animal models that may clarify the retardation in nervous tissue development observed in the respective human patients. Further studies on the effects of carbohydrates on liver lysosome will be conducted in greater detail including diurnal rhythm and hepatic toxicity mechanisms.